Window goes down when starting car.

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your CTS. It sounds like you're dealing with an electrical issue affecting the rear driver's window. The fact that the window goes down when you start the car suggests there might be a short circuit or a fault in the window control system. Given that the window operates normally after driving for a while and with the defrost on, it could be linked to temperature changes affecting the electrical components or connections. To diagnose the issue, start by checking the wiring and connectors associated with the window motor and switches. Look for any damaged or frayed wires that might be causing intermittent contact. If everything appears intact, the window motor, the switch, or the control module could be at fault. It might be best to consult a trusted repair shop for a thorough diagnostic, as this type of electrical problem can sometimes be tricky to pinpoint. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!